At present, as for an OLED display substrate, an organic functional layer of the OLED display substrate is usually formed by a process such as inkjet printing. However, in the prior art, the layer formed by the ink after drying has an uneven structure (i.e., a coffee ring structure), in which the edge is thick and the middle is thin. The organic functional layer with uneven thickness is likely to cause uneven illumination of sub-pixels, thereby affecting the service life of an OLED display panel.